/ Dictionary / Index R Roscommon: Meaning and Definition of Find definitions for: Ros•com•mon Pronunciation: (ros-kom'un), [key] — n. a county in Connacht, in the N Republic of Ireland. 54,499; 950 sq. mi. (2460 sq. km). Co. seat: Roscommon. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. roscoelite rose Related Content Daily Word Quiz: gregarious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language